Instruments of this general type are used in surgery directly underneath a layer of tissue which, in general, is covered outside by the body skin and in a body cavity which may be natural or artificial. The main application for which the instruments of this type have been developed relates to work on the penetrating veins of the human leg. To explain the specific applications of such instrument, the surgical endoscopic treatment of penetrating veins is elucidated below.
Blood from the human leg is discharged through a parallel vein system. Deep veins carry most of the blood flow to be carried away. Surface veins that run in the vicinity of the skin only contribute 10% to the blood removal. Cross-connections are present in several places between the deep and the surface veins and are the so-called perforating or penetrating veins; they comprise inward branches along their paths.
Disorders in the surface vein system entail a number of diseases ranging from merely cosmetic varicose veins to large-scale tissue destruction. A series of techniques are available to surgically remedy these problems, wherein illustratively only the penetrating veins are ligated or the outer veins are removed in full. In each case, work is required on the penetrating veins to ligate or sever them and to seal the severed ends.
Open surgery on such work on the penetrating veins is complex and leaves scars behind. For this reason, endoscopic technology is gaining acceptance.
The known and standard instrumentation used in endoscopic work in this field, and which may be considered the precursor of the instrument of the type described herein, was described in the report, "Endoscopic Subfascial Sectioning of Incompetent Performing Veins in Treatment of Primary Varicosis", M. Jugenheimer, Th. Junginger, World J. Surgery. 16, pp 971-975, 1992. This instrument is composed of a proximal, open sleeve with a grip, optics with grip and with a surgical implement inserted into the sleeve. Surgery takes place in the space between the muscle and the fascia enclosing the muscle, this space being easily enlarged into a surgical space by lifting the fascia from the muscle.
This instrumentation entails drawbacks because several elements must be held and actuated, requiring more than two hands. Moreover, the sleeve is open and as a result gas evacuation, for instance to remove smoke and vapor during electro-surgery or gas to allow insufflation to widen the surgical space, are precluded.
An instrument of this species is described in the document WO 95/14425. This instrument comprises a sleeve with integrated optics. Both parts may be thus operated with one hand. The other hand remains free to operate the surgical implement, such as scissors, a knife or a high-frequency (hf) cutting electrode to sever the penetrating vein, or a coagulating implement or a clip applicator to seal the penetrating vein, and the like. Improved sealing is attained by the integrated design. For instance, a rubber lip sealing the surgical implement may be mounted at the proximal end of the operating duct. Insufflation and evacuation are improved thereby.
In this design the optics is mounted in the cross-sectional zone of the sleeve near the outlets, whereas the operating duct is mounted opposite the outlets. The design is simplified because the operating duct is not in the way of guiding the image and light guides from the optics into the outlets.
It is standard procedure to insert such an instrument through a pierced duct underneath the skin and the muscle fascia into the space between the muscle and the fascia and to advance the instrument therein up to a penetrating vein to be operated on and, possibly, thereafter to be advanced farther to another penetrating vein to be operated on. In the process and by its nature the instrument will rest with its outer proximal end projecting from the skin directly against the leg. For reasons of space and handling, the outlets must be directed away from the leg.
Accordingly, the instrument inner duct of known design points toward the inside of the leg whereas the optics points toward the outside of the leg, that is, toward the fascia. As a result, however, an implement, such as a clip applicator, inserted through the operating duct into the space between the fascia and the muscle where the penetrating vein will be operated on, lies against the muscle. Only at this location is it possible to conveniently operate on the penetrating vein.
On the other hand, operating is disadvantageous at this site, near the muscle, of the penetrating vein, because this vein has branches in the region between fascia and muscle. Supply to the penetrating vein must take place outside those branches, that is as far as possible outside at the fascia.
But in the known instrument, which is located toward the muscle, surgery on the fascia-near zone of a penetrating vein is possible only at great pains. High leverage forces must be applied to the instrument, entailing difficulty and possibly unwanted injuries.
German patent document 29 26 919 C2 discloses an endoscopic instrument wherein the optics, the image guide and a separately emplaced light guide are mounted in the tubular sleeve on one side of its cross-section, whereas the operating duct is located on the other side of the cross-section. However, differing from the design of patent document WO 95/14425, the outlet of the light guide is on the other side of the tubular sleeve, where the operating duct is located. In relation to the tubular sleeve the two outlets therefore are diametrically opposite. Obviously such an instrument is presently inapplicable because the light guide outlet would be in the immediate vicinity of the body on account of the required angular position with the image guide outlet away from the body.